PubMed Health⌕ Search

Biomedical subjects

K Saigo

Publications and source records attributed to K Saigo.

At least 19 recordsLinked to original sources
PubMed2006

Comprehensive analysis of microRNA expression patterns in hepatocellular carcinoma and non-tumorous tissues.

MicroRNAs (miRNAs) are a non-coding family of genes involved in post-transcriptional gene regulation. These transcripts are associated with cell proliferation, cell differentiation, cell death and carcinogenesis. We analysed the miRNA expression profiles in 25 pairs of hepatocellular carcinoma (HCC) and adjacent non-tumorous tissue (NT) and nine additional chronic hepatitis (CH) specimens using a human miRNA microarray. Targets and references samples were co-hybridized to a microarray containing whole human mature and precursor miRNA sequences. Whereas three miRNAs exhibited higher expression in the HCC samples than that in the NT samples, five miRNAs demonstrated lower expression in the HCC samples than in the NT samples (P<0.0001). Classification of samples as HCC or NT by using support vector machine algorithms based on these data provided an overall prediction accuracy of 97.8% (45/46). In addition, the expression levels of four miRNAs were inversely correlated with the degree of HCC differentiation (P<0.01). A comparison of CH and liver cirrhosis samples revealed significantly different pattern of miRNA expression (P<0.01). There were no differences, however, between hepatitis B-positive and hepatitis C-positive samples. This information may help clarify the molecular mechanisms involved in the progression of liver disease, potentially serving as a diagnostic tool of HCC.

Adult↗
PubMed2006

Troglitazone inhibits cell growth and induces apoptosis of B-cell acute lymphoblastic leukemia cells with t(14;18).

Peroxisome proliferator-activated receptor-gamma (PPARgamma), a member of the nuclear receptor superfamily, has been detected in several human leukemia cells. Recent studies reported that PPARgamma ligands inhibit cell proliferation and induce apoptosis in both normal and malignant B-lineage cells. We investigated the expression of PPARgamma and the effects of PPARgamma ligands on UTree-O2, Bay91 and 380, three B-cell acute lymphoblastic leukemia (B-ALL) cell lines with t(14;18), which show a poor prognosis, accompanying c-myc abnormality. Western blot analysis identified expression of PPARgamma protein and real-time PCR that of PPARgamma mRNA on the three cell lines. Troglitazone (TGZ), a synthetic PPARgamma ligand, inhibited cell growth in these cell lines in a dose-dependent manner, which was associated with G(1) cell cycle arrest and apoptosis. We also found this effect PPARgamma independent since PPARgamma antagonists failed to reverse this effect. We assessed the expression of c-myc, an apoptosis-regulatory gene, since c-myc abnormality was detected in most B-ALL cells with t(14;18). TGZ was found to dose-dependently downregulate the expression of c-myc mRNA and c-myc protein in the three cell lines. These results suggest that TGZ inhibits cell growth via induction of G(1) cell cycle arrest and apoptosis in these cell lines and that TGZ-induced apoptosis, at least in part, may be related to the downregulation of c-myc expression. Moreover, the downregulation of c-myc expression by TGZ may depend on a PPARgamma-independent mechanism. Further studies indicate that PPARgamma ligands may serve as a therapeutic agent in B-ALL with t(14;18).

Adolescent↗
PubMed2005

Genotoxicity studies on dietary diacylglycerol (DAG) oil.

Dietary diacylglycerol (DAG) oil is an edible oil enriched in DAG (more than 80%). A recent investigation indicated that DAG oil or its components may have beneficial effects on the prevention and management of obesity. We evaluated the genotoxic potential of DAG oil using standard genotoxicity tests. Bacterial reverse mutation assay (Ames test), the chromosomal aberration assay in cultured Chinese hamster lung cells (CHL/IU), and a bone marrow micronucleus assay in ICR CD mice were employed in the present study. In addition we have tested the possibility that genotoxic substances may be formed during cooking, heated DAG oil (HDG) was prepared by batch frying potato slices in the oil at 180 degrees C for 8 h/day for three consecutive days. Therefore, genotoxicity tests were also performed on HDG. Results obtained did not show any genotoxic effect on either unheated DAG oil (UDG) or HDG. We conclude that there are no safety concerns on the genotoxicity of DAG oil under the conditions for normal use.

Animals↗
PubMed2005

Large scaled analysis of hepatitis B virus (HBV) DNA integration in HBV related hepatocellular carcinomas.

BACKGROUND AND AIMS: Hepatitis B virus (HBV) DNA integration into or close to cellular genes is frequently detected in HBV positive hepatocellular carcinomas (HCC). We have previously shown that viral integration can lead to aberrant target gene transcription. In this study, we attempted to investigate common pathways to hepatocarcinogenesis. METHODS: By using a modified Alu-polymerase chain reaction approach, we analysed 50 HCCs along with 10 previously published cases. RESULTS: Sixty eight cellular flanking sequences (seven repetitive or unidentified sequences, 42 cellular genes, and 19 sequences potentially coding for unknown proteins) were obtained. Fifteen cancer related genes and 25 cellular genes were identified. HBV integration recurrently targeted the human telomerase reverse transcriptase gene (three cases) and genes belonging to distinct pathways: calcium signalling related genes, 60s ribosomal protein encoding genes, and platelet derived growth factor and mixed lineage leukaemia encoding genes. Two tumour suppressor genes and five genes involved in the control of apoptosis were also found at the integration site. The viral insertion site was distributed over all chromosomes except 13, X, and Y. CONCLUSIONS: In 61/68 (89.7%) cases, HBV DNA was integrated into cellular genes potentially providing cell growth advantage. Identification of recurrent viral integration sites into genes of the same family allows recognition of common cell signalling pathways activated in hepatocarcinogenesis.

Adolescent↗
PubMed2004

Activation-induced cytidine deaminase expression in follicular lymphoma: association between AID expression and ongoing mutation in FL.

Activation-induced cytidine deaminase (AID) is required for somatic hypermutation (SHM) and class switch recombination (CSR) of the immunoglobulin (Ig) gene. AID has been reported to be specifically expressed in the germinal center (GC). Follicular lymphoma (FL) cells are known to be exposed to GC reaction, as characterized by a high degree of SHM with some heterogeneity in terms of intraclonal microheterogeneity and antigen selection. The heterogeneity of SHM pattern in FL intrigued us to investigate the AID expression. AID expression was investigated in 19 FL materials consisting of 15 cases of FL fresh cells and four cell lines. In all, 10 fresh cells and three cell lines expressed AID, but the others did not. SHM was investigated in 12 fresh cells and four cell lines. The ongoing mutation was significantly different between AID-positive and AID-negative FL fresh cells (unpaired Student's t-test, P=0.047). Ongoing mutation was not seen in any of the cell lines. AID expression was associated with the ongoing mutation in FL fresh cells (two-tailed Pearson's coefficient correlation, r=0.899, P=0.01). The switch off of AID expression may start in the B-lineage differentiation stage counterpart of FL after optimizing SHM, indicated by the cessation of the ongoing mutation in AID-negative FL fresh cells.

Aged↗
PubMed2004

Quantitative nested reverse transcriptase PCR vs. real-time PCR for measuring AML1/ETO (MTG8) transcripts.

A quantitative nested reverse transcriptase polymerase chain reaction (QN-RT-PCR) method was developed using a plasmid cDNA containing the AML1/ETO (MTG8) fusion transcript from Kasumi-1 cells, an acute-myelogenous leukemia cell line with the t(8;21) translocation. In this method, the plasmid was detectable at a concentration of 10(-17) m. The fusion transcript in a mixture of 10(7) Rice94 (Burkitt lymphoma cell line) cells containing two Kasumi-1 cells was detectable at 10(-17) m. In a previously published real-time PCR method, the plasmid containing the fusion transcript was detectable at 10(-16) m or higher, and 20 or more Kasumi-1 cells were detectable in 10(7) Rice94 cells. Thus, this QN-RT-PCR method is more sensitive than the real-time PCR. When the same samples were examined by real-time PCR and our QN-RT-PCR method, in one patient in clinical remission after chemotherapy and allogeneic-bone marrow transplantation (BMT), the transcript was detected by QN-RT-PCR 60 days prior to hematological relapse, in contrast to 10 days before hematological relapse by real-time PCR. The transcript level was below 10(-17) m (undetectable) with this QN-RT-PCR in patients in clinical remission after chemotherapy and BMT, while it was 10(-15)-10(-16) m in patients in clinical remission after chemotherapy alone. The quantitative difference of the transcript level in minimal residual disease (MRD) between these two different types of clinical remission was estimated to be at least 10(2)-fold. This QN-RT-PCR method is useful for predicting hematological relapse and for quantitatively estimating MRD in different types of clinical remission.

Cell Line, Tumor↗
PubMed2002

Fluctuations in plasma macrophage colony-stimulating factor levels during autologous peripheral blood stem cell transplantation for haematologic diseases.

Plasma macrophage colony-stimulating factor (M-CSF) levels were measured in 13 haematologic patients treated with autologous peripheral blood stem cell transplantation (PBSCT). Six of the patients showed an increase in M-CSF peak levels (>3000 pg/ml) during the conditioning and stem cell infusion period. The peak levels of M-CSF in this phase correlated with thrombomodulin levels, indicating the endothelial origin of plasma M-CSF. However, the M-CSF levels were not influenced by TNFalpha. More patients with high M-CSF levels (>5000 pg/ml) suffered from organ failure than those with lower M-CSF levels. These results suggest that high M-CSF levels may correlate with cellular or organ damage in patients treated with PBSCT.

Adult↗
PubMed2002

Usefulness of automatic detection of fragmented red cells using a hematology analyzer for diagnosis of thrombotic microangiopathy.

We previously reported an automatic method for quantitative analysis of schistocytes or fragmented red cells using an automatic hematology analyzer, XE-2100. In the study reported here, we evaluated the accuracy of this detection method in patients with thrombotic microangiopathy (TMA). A follow-up study was performed on 14 patients with two types of TMA, thrombotic thrombocytopenic purpura or hemolytic uremic syndrome. Schistocyte percent was evaluated both with an automatic counter and by means of microscopic observation. Total activity and isoenzyme pattern of lactate dehydrogenase (LD) were also determined. In these patients, schistocyte percent determined by automatic counting correlated highly with that determined by manual counting under microscopic observation (r = 0.852, P < 0.0001). Schistocyte percent was shown to correlate significantly with isoenzyme fractions 1 and 2 of LD (r = 0.732, P < 0.02), reflecting hemolysis. Nine of 11 patients tested had high concentrations of LD isoenzyme five without distinct liver damage, and schistocyte percent did not relate to fraction 5 of LD. Automatic detection of schistocyte percent using a hematology analyzer was useful for an accurate diagnosis and follow-up of thrombotic microangiopathy. The origin of LD fraction 5 remains to be determined.

Adult↗
PubMed2001

Identification of human cancer-related genes by naturally occurring Hepatitis B Virus DNA tagging.

Proviral tagging has been used in animals as a powerful tool for cancer genetics. We show that a similar approach is possible in patients with hepatocellular carcinoma (HCC) infected by Hepatitis B Virus (HBV), a human pararetrovirus which may act by insertional mutagenesis. In this work, the HBV genome is used as a probe to identify cancer-related genes. By using HBV-Alu-PCR, we obtained 21 HBV/cellular DNA junctions from 18 different patients. In six of 21, we found the HBV DNA integrated into a cellular gene: (1) Sarco/Endoplasmic Reticulum Calcium ATPase1 Gene; (2) Thyroid Hormone Receptor Associated Protein 150 alpha Gene; (3) Human Telomerase Reverse Transcriptase Gene; (4) Minichromosome Maintenance Protein (MCM)-Related Gene; (5) FR7, a new gene expressed in human liver and cancer tissues; and (6) Nuclear Matrix Protein p84 Gene. Seven junctions contained unique cellular sequences. In the remaining eight, the HBV DNA was next to repetitive sequences, five of them of LINE1 type. The cellular genes targeted by HBV are key regulators of cell proliferation and viability. Our results show that studies on HBV-related HCCs allow to identify cellular genes involved in cancer. We therefore propose this approach as a valuable tool for functional cancer genomic studies in humans.

Base Sequence↗
PubMed2001

P21WAF1/CIP1 messenger RNA expression in hepatitis B, C virus-infected human hepatocellular carcinoma tissues.

BACKGROUND: The primary objective of this study was to clarify the significance of p21WAF1/CIP1(p21) gene expression in the tumorgenicity of hepatitis B virus (HBV) and hepatitis C virus (HCV) infected human hepatocelluar carcinoma (HCC). METHODS: The authors performed Northern blot hybridization to compare the p21 messenger (m) RNA expression levels among 16 HCC cases. They detected tissue HBVx mRNA (Northern blot) and plus- and minus-strand HCV RNA (reverse transcription-polymerase chain reaction) in liver tissues. They also measured alanine transaminase (ALT) levels and indocyanine green retention rate at 15 minutes (ICG-R15). RESULTS: The p21 transcripts of tumor (T) tissues could be identified with lower intensity than nontumor (N) tissues in all 4 HBVx mRNA(+) cases, 8 of 10 HCV RNA(+) cases, and 1 of 3 B(-), C(-) cases (1 case was positive for both viruses). p21 mRNA expression levels of N tissues were significantly higher in HCV RNA(+) cases than in HBVx mRNA(+) cases. p21 mRNA expression levels of N tissues were significantly correlated with serum ALT levels. CONCLUSIONS: In HCV hepatitis, p21 mRNA expression is up-regulated to control cell cycle under regeneration stress. Once the liver develops HCC, the p21 mRNA expression decreases to prominently low levels. The up-regulated p21 expression may play a role as a guard to prevent hepatocytes from tumorgenicity in HCV hepatitis.

Adult↗
PubMed2001

Prophylactic excision of the gallbladder and bile duct for patients with pancreaticobiliary maljunction.

HYPOTHESIS: Pancreaticobiliary maljunction (PBM) is a high-risk factor for biliary tract carcinogenesis because of a continuous reflux of pancreatic juice into the biliary tract. It remains to be disclosed whether we should perform prophylactic excision of gallbladders and bile ducts. DESIGN: A person-year method. SETTING: A university hospital. PATIENTS: We studied 68 patients with PBM treated between August 1, 1974, and December 31, 1999. MAIN OUTCOME MEASURES: Relative risks (observed number-expected number ratios) of gallbladder and bile duct carcinomas according to type of bile duct dilation (ie, cystic dilation, diffuse dilation, and nondilation). RESULTS: Observed number-expected number ratios of gallbladder carcinomas were high: 291.3 in 43 patients with cystic dilation, 167.2 in 16 patients with diffuse dilation, and 419.6 in 7 patients with nondilation. Observed number-expected number ratios of bile duct carcinomas were 194.2 in 43 patients with cystic dilation before surgery and 142.8 in 39 patients with cystic dilation after long postsurgical follow-up. All these values were statistically significant (P<.01). CONCLUSIONS: The gallbladder carries a high risk for carcinogenesis in all types of dilation in patients with PBM. The bile duct carcinomas of PBM were exclusively identified by the type of cystic dilation. Prophylactic cholecystectomy should be recommended for all dilation types, and prophylactic excision of bile ducts including cholecystectomy should be performed in patients with PBM and cystic dilation. Complete excision of extrahepatic dilated bile ducts and careful follow-up for carcinogenesis in residual dilated bile ducts should be recommended for patients with PBM and cystic dilation.

Adult↗
PubMed2001

Diversification of cell types in the Drosophila eye by differential expression of prepattern genes.

According to Freeman (Development, 124 (1997) 261), reiterative use of Spitz signals emanating from already differentiated ommatidial cells triggers the differentiation of around ten different types of cells. Here we show evidence that the choice of cell fate by newly recruited ommatidial cells strictly depends on their developmental potential. Using forced expression of a constitutively active form of Ras1, three developmental potentials (rough, seven-up, and prospero expression) were visualized as relatively narrow bands corresponding to regions where rough-, seven-up- or prospero-expressing ommatidial cells would normally form. Ras1-dependent expression of ommatidial marker genes was regulated by a combinatorial expression of eye prepattern genes such as lozenge, dachshund, eyes absent, and cubitus interruptus, indicating that developmental potential formation is governed by region-specific prepattern gene expression.

Animals↗
PubMed2001

Quantification of red blood cell fragmentation by automated haematology analyser XE-2100.

The extent of red blood cell fragmentation in peripheral blood is useful for diagnosis and follow-up in many diseases, e.g. haemolytic uremic syndrome, transplantation-associated thrombotic microangiopathy (BMT-TMA). However, this quantification still relies on manual counting of fragmented red cells on blood smears. We have developed a quantification system by gating a fixed area of fragmented red blood cells (Gate 1) on an automated haematology analyser (XE-2100, Sysmex Co., Kobe, Japan). The fragmented red cell percentage (FRC%) calculated with this system, from 100 samples, was highly correlated with the manual count (r=0.902, P < 0.0001). Because microcytic anaemia specimens usually occupy a lower position on the XE-2100 scattergram, with microcytic cells overlapping Gate 1 and causing a spuriously high FRC% calculation, a supplementary gate (Gate 2) was added. Using the particle number in this gate as well as in Gate 1, a revised method for such samples was developed and its validity confirmed (revised FRC% correlated with a manual count for 10 subjects (P < 0.001). Because this gating system can be programmed on any XE-2100, it is likely to prove useful for accurate quantification of red blood cell fragmentation and for the monitoring of the development of BMT-TMA.

Anemia, Iron-Deficiency↗
PubMed2001

Stereoselective synthesis of dinucleoside phosphorothioate using enantiopure 1,2-amino alcohols as chiral auxiliaries.

Diastereopure nucleoside 3'-cyclic phosphoramidites were synthesized stereoselectively from enantiopure 1,2-amino alcohols. In the presence of a novel activator, these phosphoramidites underwent the condensation with 3'-O-tert-butyldimethylsilylthymidine to give the corresponding phosphite intermediates. Upon sulfurization, followed by deprotection, dithymidine phosphorothioate was obtained in good yield with good to excellent diastereoselectivity.

Amino Alcohols↗
PubMed2001

Synthesis of a new type of artificial nucleic acid derived from optically active serine.

This paper describes the synthesis of a new type of nucleic acid analog derived from L-serine with ester linkages. The monomer unit bearing thymine base was synthesized from L-serine ethyl ester by a three-step reaction in good yield without racemization. 3-Nitro-1,2,4-triazol-1-yl-tris(pyrrolidin-1-yl)phosphonium hexafluorophosphate (PyNTP) was found to be highly effective for the rapid ester bond formation without racemization. 2-Phenyl-2-(trimethylsilyl)ethyl group was successfully employed as a carboxyl protecting group in solution-phase synthesis.

DNA↗